DETERMINATION OF PICOMOLE CONCENTRATIONS OF ALUMINUM (III) IN HUMAN SALIVA AND URINE BY A LUMINOL-CARBOXYMETHYL CHITOSAN CHEMILUMINESCENCE SYSTEM

Abstract

A luminol–carboxymethyl chitosan (CMCS) system was established using flow injection chemiluminescence (CL) based on the enhancing effect of CMCS on the luminol–dissolved oxygen reaction. The CL intensity was linear with the CMCS concentration ranging from 0.01–30.0 µM. Al(III) was shown to quench the CL of the luminol–CMCS reaction, and the decrease of CL intensity was linear with the logarithm of Al(III) concentration over the range from 10–1000 pM with a detection limit of 3.5 pM (3σ). At a flow rate of 2.0 mL min−1, the analysis was performed within 30 s. The proposed CL method was successfully applied to the determination of picomole levels Al(III) in human saliva and urine after oral intake of two aluminum hydroxide tablets, with recoveries from 90.6–108.7% and relative standard deviations <3% (n = 5). The results indicated that the excreted Al(III) in saliva and urine reached its maximum values at 3 hr and 2 hr, and the total excretive ratio were 1.24 × 10−3% and 3.45% in 6 hr and 12 hr, respectively. The elimination rate constant k and the half–life time t 1/2 in human saliva and urine were 0.3747 hr−1, 1.8495 hr, 0.7132 hr−1, and 0.9717 hr, respectively. The possible CL mechanism of the luminol–CMCS–Al(III) reaction is discussed.